A colonoscope is a medical device specifically designed to allow a visual inspection of the lining of the colon (the 'bowel wall') without the need for conventional surgery. Like a gastroscope, it is a type of endoscope, that is a long tube equipped with a miniature real-time video camera (and light) and with a range of remotely operated surgical tools to allow some small procedures to be carried out during the colonoscopy examination itself. These procedures include removing polyps and taking biopsies, or tissue samples, for laboratory analysis.

Colonoscopies are recommended for a variety of reasons, including:

  • A positive result from an FOBT (Faecal Occult Blood Test), which detects very small amounts of blood in bowel motions.
  • A family history of serious bowel conditions such as cancer.
  • Bleeding from the rectum or anus.
  • Polyps that have been detected and / or removed in previous colonoscopies.

Preoperative Instructions

The day before the colonoscopy, the bowels must be completely emptied using a special medication. Read about Preparation for your colonoscopy.


A colonoscopy is conducted under light anaesthesia and generally takes approximately 20-30 minutes. Once the anaesthetic has worn off, patients are kept under observation for around two hours before being allowed to leave.

Postoperative Instructions

Due to the effects of the anaesthetic, patients must not drive themselves home and cannot drive the following day either. Patients may return to work the following day however it is advisable not to schedule any important meetings or decisions the day after the procedure.


Having a colonoscopy is a very low risk procedure.  The risks include:

These risks increase slightly where one or more polyps are removed.

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